We examine the effect of varying levels of immersion on the perfor- mance of a target following task in augmented reality (AR) X-ray vision. We do this using virtual reality (VR) based simulation. We analyze participant performance while varying the field of view of the AR display, as well as the reliability of the head tracking sensor as our components of immersion. In low reliability conditions, we simulate sensor dropouts by disabling the augmented view of the scene for brief time periods. Our study gives insight into the effect of tracking sensor reliability, as well as the relationship between sensor reliability and field of view on user performance in a target following task in a simulated AR system.